In dermis, density of capillary blood vessels is higher as compared with epidermis and subcutaneous tissue, and terminals of lymph vessels are present, so that it is known that particularly a directly injected drug moves to blood vessels or lymph vessels relatively fast, and the absorption rate to absorb the drug in body fluids becomes faster. Especially, in dermis, it is possible to cause drugs using macromolecular material, such as hormone, antibody medicine, cytokine, etc., to be efficiently absorbed in blood. Further, it is known that dermis is a place of relatively effective immunity, and it is possible to save a dosage of vaccine and to increase sensitization of vaccine.
Also, it is known that in a grown-up man, dermis is present at a given depth from the body surface (surface of a stratum corneum). This means in other words that when injecting a drug into dermis, it is possible to use puncture needles of the same length (depth) to adults.
Generally, the thickness of dermis is about 1 mm-4 mm (average value is 1 mm-2 mm) with reference to a vertical direction relative to the body surface. Further, in general skin structure, dermis is present in the skin, being sandwiched between epidermis with the thickness of about 0.06 mm-0.1 mm including a stratum corneum, and subcutaneous tissue. Accordingly, it is difficult to correctly insert a drug solution supplying opening of a puncture device, for example, a needle tip of a puncture needle, into dermis that is present between epidermis and subcutaneous tissue, and if the needle tip is accidentally inserted in subcutaneous tissue, etc., a problem is caused that a drug cannot be efficiently absorbed.
Recently, it is tried to administer medicine using the above-described macromolecular material to dermis as a target, in a sustained manner or as one-shot administration, however, in such a case, the above-described problem becomes conspicuous.
Background puncture devices of this kind include, for example, the one described in Patent Document 1. Patent Document 1 describes a puncture device for which the present applicant previously filed a patent application. The puncture device according to Patent Document 1 (hereinafter called as “first background example”) is a puncture device puncturing skin with a puncture needle. The puncture device includes a puncture needle moving means movably holding a puncture needle, a fixing unit having a flat plane to be fixed to the body surface and in which the puncture needle moving means has been provided, and a hinge provided to the fixing unit and configured to raise the skin upward relative to the body surface by rotating, and is configured such that the puncture needle is moved along the flat plane of the fixing unit to puncture the skin raised by the hinge.
Other examples of background puncture devices include the one described in Patent Document 2. Patent Document 2 describes an injection device and an injection method. The injection device according to Patent Document 2 (hereinafter referred to as “second background example”) is an injection device for giving an injection to skin at a given depth, including a skin positioning means for carrying out positioning relative to a part in a region of skin such that at least a portion of the part of the skin can be held raised above or dented below the region of the skin, an injection needle, and a means for guiding the injection needle to slide beneath the skin positioning means to an injection position where an end of the needle lies at a given distance below the skin positioning means.    Patent Document 1: Japanese Patent Laid-Open No. 2007-117616    Patent Document 2: Japanese Patent Laid-open No. 2005-518253